Improvement in mariners  cojvipasses



2 Sheets-Sheet l S. LONGFELLOW. Mariners Compass.

- 'No. 217,015. Patehted July 1, 1879.

B v Fi S) LONGFELLOW. 2SheetsSheet2 Mariners Compass,

No. 217,015. Patented July 1, I879 N-FETERS, FHOTO-LITHOGRAPHER,WASHINGYON. O C.

STEPHEN LONGFELLOW, OFST. LOUIS, MISSOURI, ASSIGNOR OF A PART OF "UNITEDSTATES PATENT OFFICE;

HIS RIGHTTO FRANCIS AMORY, OF BEVERLY, AND SAMUEL SNOW, OF

CAMBRIDGE, MASSACHUSETTS.

IMPROVEMENT IN MARI N'ERS 0%MPASSES.

Spe cification forming part of Letters Patent No, 2 l7 ,0l5, dated July1, 1879; application filed November 16, 18 77.

.To all whom it may concern:

Be it known that I, STEPHEN LONGFELLOW, of the city of St. Louis, in theState of Missouri, have invented certain new and useful Improvements inMariners Compasses, of

which the following is a full, clear, and exact description, which willenable those skilled in the art to which the invention appertains tomake and use the same, reference being had to the drawings accompanyingand forming part of this specification.

For the purpose of preventing the deviation pass-bowl, and so arrangedthat their attractive influenceupon theneedle shall neutralize theeffects of the local attraction referred to.

My first improvement relates to magnetic bars of this description; andconsists, in the manner hereinafter to be more fully set forth, ofarranging these bars in relation to each other and to the compass-bowl,and of attaching them thereto by devices which render them capable ofadjustmentin various directions to meet the various forms of localattraction, by

which manner of arrangementand method of attachment, besides overcomingand neutralizing the effects of local attraction, they also exercise adirect influence in correcting the. dip of the needle and maintainingthe compass-card in a'horizontal position-a result which will be foundof advantage in high latitudes.

A further improvement relates to the'manner of weighting or ballastingthe compassbowl; and consists in the use for this purpose of a hollowglobe, which is attached to the bottom of the compassbowl, and containsfine shot, the quantity of which can be varied at pleasure, so that theweight of the bowl can be perfectly regulated as necessity requires,

thereby rendering the same compass equally serviceable in light or inheavy weather, and obviating the necessity of having two compasses, oneheavy and the other light, as is now often the case.

' Another improvement relates to the manner of illuminating thecompass-card and consists in eflecting this by lamps attached on eachside of the coverof the bowl, and by providing the interior of thiscover with a reflecting-surface, in the manner described hereinafter.

y In the accompanying drawings, Figure 1 is a view in elevation of thecase containing the compass, showing the top or cover of the case inposition. Fig.2 is a view of the case, in perspective, with the topremoved, and shows the compass-bowl contained in the case and theazimuth-circle and sight-vanes attached to the compass-bowl. Fig. 3 is aview'of the compass-bowl detached from the case, and shows the form ofthe bowl and the arrangement of and manner of attaching the magneticbars. Fig. at is a detached view of one of the magnetic bars; and Fig. 5is a detached view, in section, of the spindle and weight.

In these drawings the same letters in the several figures refer to thesame parts.

A is the case or shell containing the coinpass, whichcase maybe of ovoidfOlilIl, as shown, or of spherical form, if preferred, and is made intwo parts, B and O, removable one from the other, but capable of, beingclosely connected together by any suitable fastening device, as

shown at a, Figs. 1 and 2, so that a complete protection from theweatheris afforded for the compass contained therein. This case may be mountedupon a suitable standard, and is then designed to take the place of thepresent standard-compass, or of the old wooden binnacle or, bydispensing with the upper half,

B, it can be placed in a box and used in the old binnacle, as preferred.

0, Figs. 2 and 3,is the compass-bowl, which is suspended within the caseby gimbals, in the usual manner, D being a gimbal-ring, which, in Fig.3, is shown out of position, in order that the magnetic bars may beclearly shown.

I (shown at G) which is capable of being opened longitudinally to admitof the easy removalof the bar, and when closed is fastened by apin, 1).Attached to this sleeve by ajoint, 0, is a short arm, H, at right anglesto the sleeve,

and this arm is hinged at d to an oblongcurved plate,

By means of these plates the mag nets are secured to the compass-bowl inthe 4 following manner: Around the compass-bowl,

and just below the gimbals, are three parallel bands, K K K, separatedfrom each other by a distance just equal to the width of the plate, andby these bands groovcsare formed for the reception of the plate. Thecurve given to the plate is such that when it is applied to the surfaceof the bowl it fits closely, and is kept against the surface by thebands, but can slide in the grooves formed by the bands, so that thebars can be placed in any position in the groove, as may be desired,according to the force of the.local attraction which is to be overcome.

, The upper and lower bands, K K, do not extend entirely around thecompass-bowl by the length of the plate 1., as shown at L, Fig. 3, whichspace permits of the insertion and removal of the plates.

For the purpose of affording a more secure attachment of these plates,their edges may be beveled off and the bands cut in, so that the plateswill dovetail between the bands.

I have adopted this manner of attaching the bars to the bowl as aconvenient manner of obtaining the facility of circumferentialadjustment; but other methods of attachment which will secure the sameresult may be adopted.

By means of the joints in the arms H each of these magnetic bars can beelevated to the plane of the card or depressed below that plane, andthedistance of each from the bowl can also be varied. These differentpositions of the bars are shown at F and F in Fig. 3. Bythe simpledevice above described each bar is rendered adjustable in threedirection sviz., circumferentially, horizontally, and vertically-andconsequently a perfect adjustment of the needle to the true north and ofthe compass-card to a horizontal position can be obtained for every formand degree of local attraction and in any latitude.

The magnetic bars have their poles arranged as indicated in Fig. 3; andto prevent them from coming in contact with each other at theirextremities, pear-shaped pieces of glass or porcelain, about one inch inlength and three-quarters of an inch in diameter, (shown at M.) arescrewed onto each end of each of the bars.

Anotherseries of magnetic bars, similar to those hereinbefore described,may be attached to the compass bowl above the first series by the grooveformed by the bands K K; When this is done, two magnets can be broughtto-- gether, thereby doubling the power at any given point, and by theremoval of one or more magnets from the series the power can beconcentrated at will. This magnetic attachment may be applied to anyformof compass now in use.

By means of this arrangement of magnets the shipmaster will, beforeleaving port, be enabled to determine by experiment theexact amount oflocal deviation for each point of the compass, and, by means of a falsecard, which will be furnished with each compass sold, will be enabled toshape his course with absolute certainty.

As shown in Fig. 3, the compass-bowl 0, instead of being of the usualhemispherical form, terminates in an elongated neck, .r, by which formincreased steadiness is obtained, and'into the apex of the bowl isscrewed a spindle, N,'to which spindle the weight used for ballastingthe compass is attached. This weight consists of a hollow brass globe,O, constructed in two parts, connected by a screw, and contains aquantity of fine'shot, the amount of which may be varied at pleasure,according to the amount of ballast which it is necessary for thecompass-bowl to have, and thus the compass can be kept perfectlyballasted and-is rendered equally serviceable, both in light and inheavy weather, thereby obviating the necessity of providing the vesselwith two compasses, one heavy and the other light, as is now often ,thecase.

1? is the azimuth-circle, which consists; of a removable band encirclingthe bowl just above the gimbals. It has attached to it two suitablesockets, R R, opposite to each other, for the reception of thesight-vanes S S, one of which vanes, S, is jointed, as shown at 0, so'that the ray of light can be thrown directly. across the face of thecompass, giving the exact bearing of the sun upon a circle, T, on theinner edge of the bowl, just above the card graduated to degrees andminutes. This band P fits the bowl loosely, so that the vanes arecapable of being moved around the bowl for the purpose of obtainingcorrect bearings of any object, which bearings are determined up. on thegraduated circle T.

The cover B of the compass is hemispherical and has tubular projectionsB B, Fig. 1, on each side, in which projections are fitted the lampcasesUU. The lamp-cases are provided with ventilators X X, doors W W, andhandles V V.

The lamps, one of which is shown in dotted lines at E, Fig. 1, arefitted with keroseneburners adapted to burn heavy oil. Each is securedin its case by the insertion of its oil receptacle into a hole in thebottom of the case.

The whole interior surface of. the cover is nickel-plated, so that whenthe lamps are lighted a strong light is reflected upon all parts of thecompass-card and it is perfectly illuminated.

In the after side of the cover is a square pane of glass, A, of a widthequal to onesiXth the circumference of the cover, through which glassthe eompasscard can'be observed at night, or when, in bad weather, it isnecessary to keep the compass-card covered.

Having thus described my improvements, I do not claim the combination ofsights and graduations, as this may form the subject of a separateapplication for Letters Patent; but

I claim as my invention and desire to secure by Letters Patent of theUnited States 1. In mariners compasses, one or more series of removablecurved bar-magnets attached to the outside of the compass-bowl, andcapable of adj ustment circumferentially, vertically, and horizontally,substantially as and for the purpose set forth. y

2. The combination of the magnetic bar F,

hand on this 13th day the sleeve G, the double-jointed arm H, and

curved plate t, substantially as and for the purpose set forth.

3. The combination, with the banmagnets, of the insulators M M,substantially as and for the purpose set forth.

4. The combination,with the c0mpass-bowl,

of the bands K K K on the outside of the bowl, as and for the purposeset forth, a part of each of the bands K and K being cut away to admitof the insertion and removal of the plate i, as set forth.

5. The combination, with the compassbowl, of the adjustable hollowreceptacle 0, containin g removable weights, as specified.

6. The combination, with a compass, of a concave reflector, forming acasing above the card, and side lamps arranged to throw the light bothon the card and on the reflector, as set forth.

In witness whereof I have hereunto set my of November, A. D.

' STEPHEN LONGFELLOW.

Witnesses:

R. S, VooRHIs, T. P. KENNEY.

